Femtosecond spectroscopy with vacuum ultraviolet pulse pairs

Abstract

We combine different wavelengths from an intense high-order harmonics source with variable delay at the focus of a split-mirror interferometer to conduct pump--probe experiments on gas-phase molecules. We report measurements of the time resolution (<44fs) and spatial profiles (4μm{\texttimes}12μm) at the focus of the apparatus. We demonstrate the utility of this two-color, high-order-harmonic technique by time resolving molecular hydrogen elimination from C2H4 excited into its absorption band at 161nm.